Actually there's two SOL's currently on eBay.
The 2nd one is currently "only" $500 or so:
The difference being that it has no documentation (which I suspect accounts for
the price difference), and also it only has a single card in it - a non-PT 64K
memory card (I asked the seller if it was PT or not).
In recent history SOL's have sold for anywhere from $490 to $2500!
Documentation also seems to be what has so far driven this Altair to $4K:
At least $1500, ending today....
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2071171983
From: Sellam Ismail <foo(a)siconic.com>
Reply-To: cctalk(a)classiccmp.org
To: <cctalk(a)classiccmp.org>
Subject: Re: Whats wrong with chip collecting?
Date: Sun, 17 Nov 2002 14:04:53 -0800 (PST)
>I suggest the former. Prices for old computers are fairly well
>established by now. These prices are independent of, for instance, the
>CPU that may power the computer. For example, if a SOL-20 goes on the
>market, chances are it could fetch up to $1,200, regardless of whether it
>had an Intel C8080 on the original Processor Technology CPU board or if
>it had a Cromemco ZPU with a Zilog Z80 (even a first run Z80). The CPU
>has no bearing on the valuation of the machine.